(1) Field of the Invention
This invention relates to a short-circuit protection circuit, and more particularly relates to a short-circuit protection circuit for an LED driving circuit.
(2) Description of the Prior Art
FIG. 1 is a circuit diagram of a typical DC-to-DC boost converting circuit, which includes an inductor L, a diode D, a capacitor C, a switch SW, and a controller Con, and is utilized for converting an input power source Vin into an output voltage Vout to drive an LED module Ld to illuminate. In order to have the LED module Ld generate steady illumination, the controller Con detects the level of the output voltage Vout by using a voltage detecting circuit VD to generate a voltage feedback signal VFB to control the duty cycle of the switch SW. Thus, the level of the output voltage Vout can be stabilized to have the LED module Ld generating steady illumination.
Generally, in order to make sure each of the LED units in the LED module Ld has identical LED current flowing thereon for generating identical illumination, the LED units in the LED module Ld are usually connected in serial. When anyone of the LED units is burned to result short-circuit, the other LED units suffers the additional voltage drop to result the increasing of LED current, which may shorten the lifetime of the LED units. If the LED module is not properly assembled to the output end of the DC-to-DC boost converting circuit or any other issues which may ground the output end, the voltage from the input voltage source Vin would be continuously applied to the inductor L, which may damage the inductor L and the diode D.